This invention relates to vehicle to loading dock locking units, and more particularly, to releasable vehicle to loading dock locking units having a displaceable hook for engaging a vehicle bumper.
During loading dock operations involving vehicles such as trucks or trailers, individual workers or a forklift truck are used to repeatedly enter the vehicle to load or unload materials. An extremely dangerous condition may occur if the vehicle suddenly exits the loading dock area without advising warehouse personnel or forklift operators. In the past, releasable vehicle locking devices have been developed which include a motor-actuated hook for engaging the vehicle bumper. Because of the significant and variable vertical loads imposed on a vehicle being loaded or unloaded at a loading dock, the vehicle locking device hook is occasionally downwardly deflected into an unsafe, partially engaged position which actuates a red light and a small horn. When this dangerous condition occurs, warehouse personnel must temporarily discontinue loading operations and reenergize the vehicle locking device control circuit to reset the hook into a safe, fully locked position. If warehouse personnel do not notice the red warning light or hear the warning horn and immediately reengage the hook with the vehicle bumper, it is possible for a vehicle operator to unexpectedly remove the vehicle from the loading dock and endanger workers and forklift loading equipment.
Truck hijackers have discovered that it is possible to manually reposition the vehicle locking system hook, disengage the hook from the vehicle and hijack the vehicle and its valuable contents. Although the existing locking device control circuit illuminates a red light and sounds a warning horn, such passive warning devices do not prevent hijacking.
Because existing vehicle locking systems utilize a clutch for maintaining the hook in fixed engagement with a vehicle bumper, hook displacements out of the locked position may frequently result from clutch wear or improper clutch adjustment. Expensive clutch adjustment or replacement is frequently necessary.